In a fuel cell system constituting a fuel cell electric vehicle or the like, there has been known a technology of injecting hydrogen by an electronically controlled injector, to supply the injected hydrogen to an anode of a fuel cell (see Patent Document 1). Specifically, in Patent Document 1, as a power generation amount of the fuel cell is reduced, that is, as the fuel cell is brought into a low load state, a drive cycle (drive interval) of the injector is made longer while its duty ratio is kept constant, and water in an anode flow path (fuel gas flow path) is discharged to the outside of the fuel cell. The term “power generation amount” of the fuel cell is a generic term including an actual power generation amount by the fuel cell and a requested power generation amount to the fuel cell.